Biology - Diffusion, osmosis, active transport, co-transport

What are used to measure the rate of transport of various molecules

Artificial lipid bilayers, lacking protein

What two things affect the permeability of the protein-free bilayer

1-The molecules size

2-The molecules solubility in oil

What type of molecule is the most ready to diffuse

Small, non-polar or uncharged polar molecules

What are lipid bilayers high impermeable to

All charged molecules no matter the size

Define simple diffusion

The passive net movement of ions/molecules down their concentration gradient.

What happens when equilibrium is reached

1-the net movement continues until there are equal concentrations of molecules on either side of the membrane

2-the molecules nevetheless continue to move randomly and at an equal rate in both directions across the membrane

How do small ions pass through the membrane

through aqueous protein channels

How does increasing the temperature affect the rate of simple diffusion

1-It increases the random movement of the molecules, more kinetic energy

2-As the speed of motion of the molecules increases the rate of transport by simple diffusion also increases

How does increasing the surface area affect simple diffusion

As the length of the sides of a cell or structure increase then

The surface area and volume increase exponentially

Volume then increases at a greater rate to SA

Diffusion would become less efficient as the surface area does not increase to an extent which would satisfy the increased demand of a larger cell

Describe how the steepness of the concentration gradient affects the rate of diffusion

1-The rate of entry of the molecules into the cell is directly proportional to the concentration of molecules outisde the cell